Directional and pressure control valve for hydraulic straightening presses



4 Sheets-Sheet l Jan. 1, 1952 B. wELTE DIRECTIONAL AND PRESSURE CONTROL VALVE FOR HYDRAULIC STRAIGHTENING PRESSES Filed June 1o, 1947 llll. d

Jan.' 11952 B, WEL-rE 2,580,868

DIREQTIONAL AND PRESSURE CONTROL VALVE FOR HYDRAULIC STRAIGHTENING PRESSES Filed June l0, 194'? 4 Sheets-Sheet 2 2/3 22.4' 27,6 7 9 i 2 Y J @um l 6/ 4,?7 I

INVENTOR. E eneafz'c M/eZfe.

Jan. 1, 1952 B. WELTE 2,580,868

Y DIRECTIONAL AND PRESSURE CONTROL VALVE FOR HYDRAULIC STRAIGHTENING PRESSES Filed June l0, 194'? 4 Sheets-Sheet 3 INVENTOR.

` ewed'z'cf M/elfe.

E .2. Lxf- Jan. 1, 1952 B WELTE 2,580,868

DIRECTIONAL AND'PRESSURE CONTROL. VALVE FOR HYDRAULIC STRAIGHTENING PRESSES Filed June 10, 194'? 4 Sheets-Sheet 4 #Train/Fys.

Patented Jan. 1, 1952 UNITED STATES PATNT OFFICE DIRECTIONAL AND PRESSURE CONTROL VALVE FOR HYDRAULIC STRAIGHTEN- ING PRESSES ration of Delaware Application June 10, 1947, Serial No. 753,779

This invention relates generally to straightening presses, and more particularly to an improved type hydraulic straightening press and novel control means therefor.

It is an object of this invention to provide a straightening press of the type having a hydraulically-operated piston adapted to carry a working element for straightening a workpiece supported on 'a table of the press in which improved hydraulic control means are provided for controlling the direction of movement of the piston as well as the applied force of the piston.

It is a further object of this invention to pro- Vide a control system for a straightening press of the aforementioned type whereby a single manually operated control member controls simultaneously the direction of movement of the aforementioned piston as well as the pressure exerted thereby on a workpiece.

It is a further object of this invention to provide a valve unit capable of controlling the direction of movement of an actuating piston of a straightening press or the like and simultaneously controlling the pressure applied to the piston without affecting the direction of movement of the piston.

It is a still further object of this invention to provide a hydraulic-type straightening press which is simple in operation, rugged in construction, and inexpensive to manufacture.

These and other objects of this invention will become apparent from the following detailed de-l scription taken in conjunction with the accompanying drawings in which:

Figure 1 is a side elevational view of a staightening press embodying features of one embodiment of this invention;

Fig. 2 is a front elevational view of the structure illustrated in Fig. 1;

Fig. 3 is an enlarged sectional view of the'pressure relief valve in the hydraulic circuit of this invention;

Fig. 4 is an enlarged view partially in section and partially in elevation of a further embodiment ofthe invention taken along the line 4-4 of Fig. l;

Fig. 5 is a reduced sectional view taken along.

1 Claim. (Cl. 277-60) 2 system of the embodiment illustrated in Fig. 1; and

Fig. 9 is a schematic diagram of the hydraulic system of the embodiment illustrated in Figs. 4, 5, and 6.

Referring now to the drawings, and more particularly to Figs. 1 and 2, it will be seen that a straightening press, generally indicated at Il, of a more or less conventional shape and design is provided with a generally C shaped frame I3. The upper end of the frame I3 supports a conventional hydraulic cylinder Il having a head I9 xed to a piston rod which is connected to a piston 2U, within the cylinder. Hardened steel ways 2| are mounted in thefront face of the frame I3, below the cylinder I'l, and a guide member 23, slidable in the Ways 2l, is secured to the lower end of the head I9. A stationary worktable 25, on which a fixture (not shown) may be mounted for supporting a workpiece to be straightened, is positioned beneath the head. A work engaging or straightening element 29 is provided on thev head I9.

Mounted within the frame is pump motor 35 and a fluid pump 33 for pumping fluid from a tank 3l into the cylinder Il as will be hereinafter brought out.

Mounted in the upper end of the frame I3 for controlling the movement of the head I9 is a reversing and pressure control valve unit generally indicated at 39 which will be described hereinafter in detail. The valve unit 39 is actuated by means of a vertically extending rod 4| which is secured tothe lower end of an axially slidable valve member within the unit 39. The lower end of the rod 4| is pivotally connected to a lever 43 which in turn is iixedly connected to a horizontal shaft 45 'rotatably mounted in suitable bearing means '4l carried by the opposite sides of the frame I3. Connected to the shaft 4'5 is a second lever 49 which is pivotally connected to a nected thereto. The rear end ofthe crank 51v extends rearwardly beyond the shaft 55 and is pivotally connected to a link 63, the lower end of which is adjustably and pivotally connected .to a foot pedal `(5. The pedal 65 is pivotallyl mounted on. a horizontal shaft $1 in thek same 3 manner as is the member 51 on the shaft 55, so that the valve unit 39 may be actuated either by movement of the handle 6| or the foot pedal B5, whichever is the -most convenient to the operator of the press.

It will thus be seen, that when the handle 6|, or the foot pedal B5, is pressed downwardly the linkage will cause the rod 4| to move upwardly and actuate the valve unit 39 in a manner that Will be hereinafter described.

The reversing and pressure relief valve unit 39 is shown in detail in Fig. '1, wherein it can be seen that the valve unit comprises a housing `|59. having a central axial bore 1| therethrough. Intermediate the ends of the bore 1| the housing is provided with a plurality of annular grooves 13, 15, 11, 19 and 8| which communicate with the central bore 1 I and which communicate with outlet and inlet ports in the valve body in a conventional Inanner. The groove communicates with a conduit |15, which communicates with the lower end of the cylinder l1, as best shown in Fig. 8. The groove 19 communicates with a conduit I 13 leading to the upper end of the cylinder |1, the groove 11 is connected to the outlet of pump 33 by a conduit |69, and grooves 8| and 13 communicate with an outlet conduit 83 which returns to the tank 3 I.

Axially slidable within the bore 1| of the housing is a movable valve spool 85 having three bore fitting, axially spaced, cylindrical lands 81, 89 and 9| formed thereon and joined by reduced neel:V portions 93 so as tol permit the now of uid between the lands. It will be noted, that. the effective length of landsI -89 and 9| is `reduced by notches 94 and is less than the distance between the housing grooves 19 and 8|, and 15 and 11, so as to allow overtravel of the lands -89 and 9| between the ports, for a reason which will herein after appear. The lower end of the housing l!) is recessed to receive a cover or cap member 95 therein which is provided with a conventional oil seal 91 to prevent leakage of fluid from the housing 69.

The upper end of the housing 69 is recessed at 99 and the upper end of the recess 99is-threadedv at IBI. A sleeve |113 is threaded into recess 99 and a lock nut |95 is provided forv locking the sleeve |33 in a desired position with respect to thehousing 59. The lower end of the sleeve |03l is grooved to receive a conventional O-ring seal |-91fwhich prevents the leakage of iiuid from the vhousing around the outer periphery' of thesleeve |03; The lower end of the sleeve ||l3flikewiseis formed Awith a recess |09 into which the upper reduced end of the valve spool 85 extends. A coil'spring H3. surrounds the upper end of the valye spool with its lowerend abuttillgV nects the recesses ||9 and |39 so as to permit, a,

ow of uid from the recess |19 into thevalve housing andthence to the discharge line. 83.

Secured to the `upper surface of a flange |315v on the sleeve |33,` by means of screws |23, is a conventional fluid operated, spring biased, ball type pressure relief valve generally indicated at |25. The upper end of valve |25 is provided with a tapped recess |21 to receive a coupling member |29 by which a conduit |3|Y (see Fig. 8) vmay be connected to the valve. The oppositeend of conduit |3| is connected to port |65 of a pressure control valve |33, illustrated in detail in Fig. 3.

The lower end of the valve spring |35 receives the reduced upper end of a plunger |39, and abuts against a flange |4|, formed intermediate the ends of the plunger. Flange |4| in its uppermost position, as illustrated in Fig. 7, abuts an annular shoulder |42 in the lower end of the valve |25. The lower end of the plunger I 39 is slidably supported inthe bushing I I1 and extends therethrough so as to abut the upper end of the reduced endY portion of the valve spool 85. Therefore, when the valve spool 85 is moved upwardly, the plunger |39 will compress the spring against the valve ball |49 to thereby increase the pressure from lthe conduit |3| required to unseat the ball |49. The valve shoulder |32 is provided with a groove |43, which permits iluid to ow therethrough into the sleeve recess ||9 even though flange |4| is seated against the shoulder. The force exerted by spring |35 can be altered by adjusting the position of the sleeve |03 within the housing 69, so as to adjust the pressure required to unseat the valve ball |49 for a given position of plunger I 39.

The pressure control valve |33 which controls the pressure applied to the piston 20 of the press is of a more or less conventional type and is shown K in detail in Fig. 3. The inlet port |41 of the valve |33 is connected to conduit |69 by a conduit |1I The opposed port |49 is shownas closed by means of a plug |5| The movable valve element |53 of the valve |33 is provided with a recess |54 in the upper end thereof to receive a relatively light spring |55, the upper end of which abuts against the valve housing to resiliently urge the valve element |53 downwardly to close the outlet port |51, which is connected to the tank 3 I. The movable valve element |53 is provided with a piston portion intermediate its ends, which fits. the bore of the Valve housing and is provided withra small bleed passageway |6|. The space abovethe piston portion is connected by a passageway |63 in the valve housing to the port |65, which is previously explained is connected by conduit |3| to the pressure relief valve |25 mounted in the upper end of the valve unit 39.

t will be observed that the pressure supplied to valve 39 by the pump is always the same as the pressure acting on the lower side of the piston portion of valve element |53. Moreover', the valve element |53 will always assume a position in which thepressure acting on opposite sides of the piston portion is approximately equal (spring |55 being only of suiiicient strength to insure closure of the valve when the pressure acting on opposite sides of the piston is equal). As a result, the pressure supplied to valve 39 and therefore to the cylinder |1 may be controlled by controlling the pressure acting on the upperl side of the piston portion of valve element |53. This is accomplshed by the pressure relief valve |25 in combination with the adjustable spool ofvalve 39.

Valve 39, is shown in Fig. 7 with its spool 85 in the uppermost position, in which it connects the pump outlet to the upper end of cylinder |1 and the tank to the lower end of cylinder 1, and

cylinder. When the handle 6| and pedal 65 are fully released spool 85 is shifted by spring |3 to a position in which the pressure supply groove 11 is connected to groove 15 while groove 19 is connected to groove 8|. At this time the upper end of spool 85 is entirely out of contact with plunger |39 and flange I4| rests against the flange of bushing ||1. This effects upward movement of the head |9 at minimum pressure. As the handle or pedal 55 is progressively depressed, the spool 85 moves upwardly and eventually connects groove 11 to groove 19 and groove 15 to groove 13. This connection is definitely established when the notches 94 in lands 89 and 9| are located just above the upper edges of grooves 15 and 19 respectively. At this time the end of spool 85 has just contacted but has not moved plunger |39 from the position in which flange |4| contacts the flange of bushing ||1. Under these circumstances the press head will exert its minimum downward pressure. As the handle 8| or pedal 65 is further depressed, no change in the iluid connections occurs, but spring |35 is progressively compressed, thereby progressively increasing the pressure exerted by the head |9. Thus by movement of a single control element in one direction the press may be caused to move downwardly and the amount of pressure controlled by the extent of movement of the element.

The line |15 which supplies the lower end of cylinder |1 contains a conventional foot valve which provides suincient resistance to discharge of fluid from the lower end of the cylinder to prevent the head |9 and associated parts from falling by gravity, but which offers no resistance to flow into the cylinder. The cylinder l1 is also preferably provided with an auxiliary exhaust line |14 which is located midway between the ends of the cylinder and which is in unrestricted communication with the tank at all times. The piston 29 is made of a length just less than one-half of the length of the interior of the cylinder so that it exposes the exhaust line |14 when the piston reaches either end of the cylinder. This provides an automatic pressure relief which will prevent application of a heavy force by the piston against either end of the cylinder-and makes it unnecessary to shift the reversing valve to a neutral or reversed position when the piston reaches the upper end of the cylinder.

A conventional pressure gauge |19 is connected to the valve |33 to read the pressure therein so that the operator of the press can easily control the same. A conventional needle valve IBI is connected between the gauge and the valve |33 to permit the fluid to be shut off from the gauge |19 when it is not desired.

A further embodiment of the invention is illustrated in Figs. 4, 5, 6 and 9. In this embodiment a conventional four-way valve |32 is employed for controlling the direction of movement of the piston 29. A separate conventional pressure relief valve is provided for operating the pressure control valve |33 rather than a combined valve unit, such as the unit 39 previously described, which performed the functions of both a fourway valve and a pressure relief valve. Due to the valve arrangement of this embodiment a modified linkage construction is required in order to operate the valves through a single means, such as the handle 6| or foot pedal 65 in the manner previously described. The remainder of the straightening pressure construction is sub- 6 stantially identical with that previously described, and corresponding part numbers refer to like parts of both embodiments.

The four-way valve |32 for controllingV the direction of movement of the piston 29 is located in substantially the same position as is the valve.,

unit 39 of the previous embodiment. As can be seen in Figs. .4 and 5, a conventional pressure relief valve |83 for operating the pressure control valve |33 is xedly secured to a frame member |85 disposed below and extending rearwardly of the worktable y25. The linkage for controlling the movement of the pressure relief valve |83 and the conventional four-way valve is in part the same as the linkage previously described. The rod 4|, which is connected to the lower end of the movable valve element of the four-way valve, is pivotally connected at its lower end to a generally channel-shaped lever member |81, the rearward end of which is pivotally connected to a bracket |89, which in turn is xedly connected to the frame I3 of the press. Intermediate the ends of the lever |81 a roller |9| is rotatably mounted on a shaft |92 which is xedly supported by the lever |81. Keyed to the shaft 45, which is rotatably mounted in the frame bushings 41, and disposed directly below the roller I9|, is a cam element generally indicated at 93. The cam |93 is provided with a cam surface |95 and an arcuate dwell surface |91 extending rearwardlv therefrom, which is coaxial with the shaft 45. As the shaft 45 is rotated in a clockwise direction, as viewed in Fig. 6, the cam surface |95 will move the lever` arm |81 upwardly and thus raise the rod 4| to actuate the movable valve element within the four-way valve, in the manner described for the previous embodiment. When the cam element |93 is rotated further the lever roller |9| will ride on the dwell surface |91, and the position of the rod 4| and movable valve element will not be affected. The extreme forward end of the cam surface |95 is provided with a shoulder or flange |99 adapted to act as a stop to limit the counter-clockwise movement of the cam element.

Likewise keyed to the shaft 45 and laterally spaced from the cam element |93 is a lever 29| which has a roller 293 rotatably mounted on a pin 294 xed in the upper end thereof. It will be noted that the lever 29|, as seen in Fig. 5, is keyed to the shaft 45 in an inclined position for a reason which will be hereinafter brought out.

Pivotally connected to the body of the pressure relief valve |83 by means of link 295 is an arm 291, the upper end of which has a forwardly projecting abutment element 299 adapted to engage the roller 293 on the lever 29|. Above the link 295 the arm 291 is pivotally connected to a yoke carried by the extremity of the valve-operating plunger 2 |5 which projects forwardly from the valve housing and which corresponds in function to the plunger |39 of the preferred embodiment of the invention.

The shaft 45 has a collar 211 secured thereto between the cam element |93 and the lever 29|. The collar is formed with a boss 2| 9 which is pivotally connected to a yoke 22| mounted on the end of the previously described link 5|. The forward end of the link 5| is xedly connected to the short shaft 55 which is operably connected to the handle 6| and the foot pedal 65. A tension spring 223 is connected to the body of the pressure relief valve |83 and to a pin 225 on the shaft 45 to aid in rotating the shaft 45 when the latter is actuated by the handle 8| reparation, when the handle 6l is pulled downwardly, it causes the shaft 45 to rotate in a clockwise direction. When this occurs, the cam surface |95 on the cam element |93 moves the I Qds 4.! upwardly to shift the four-Way valve into the position in which it affects downward movement of the press. After the cam surface |95 has passed; over the roller IBI, the dwell surface |97 contacts the roller so that further rotation of the shaft 4 5 will not affect the rod 4| and the four-Way valve. The lever 20| which is mounted on the opposite end of the shaft 45, due to its inclined position, will not contact the abutment 209cm the upper end of the pressure relief valve arm 201 until the four-Way valve has been thus shifted. Thereafter, further movement of the handle 6| downwardly will cause the roller 293 on the lever 20| to abut the upper end of the arm 201 and move it rearwardly so as to actuate the pressure relief valve plunger 2| 5. The operation of the pressure relief valve |83 can thus be controlled and varied without affecting the four-way valve due to the dwell surface |91 on the cam element |93 and'will control the pressure control valve |33 in the manner described in connection withthe previous embodiment.

I' claim:

A combined reversing and pressure relief valve unit including a valve housing having a longitudinal cylindrical bore therethrough, a movable valve element axially slidable in said housing bore, a plurality of bore-fitting axially spaced cylindrleal lands formed on said stem, the wall of said bore having a plurality of axially spaced annular ports therein controlled by the lands on said movable valve element, said lands being of a shorter length than the distance betweenv ce1.'-E tain of said bore ports to permit over-travel of said lands between said ports without affecting the flow of fluid through the latter when the ele.- ment establishes one set of connections, a spring biased ball-type pressure relief valve connected to said housing and communicating with said housing bore, a sleeve connected to said housing for adjustment axially of said valve element, and an axially slidable plunger within said sleeve, one end of which is adapted to be actuated by said movable valve element during said overtravel movement of the element and the opposite endof which engages said relief valve spring and is adapted to compress the latter when said plunger is moved by said movable valve element, whereby by adjusting said sleeve the amountv of compression of said relief valve spring by said overtravel movement of said Valve element may be varied.

BENEDICT WELTE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 837,429 Snyder Dec. 4, 1906` 1,921,955 Vickers Aug. 8, 1933 2,197,428 Erb Apr. 16, 1940 2,243,364 Trautman May 27, 1941 2,316,926 Willett Apr. 20, 1948 2,368,628 Bates Feb. 6, 1945 2,392,421 Stephens Jan. 8, 1946 2,426,411 Peterson Aug. 26, 194'?v 

